Seed germination percentage of multiflora rose (Rosa multiflora Thunh.) was much higher under continuous white light than in complete darkness. Red light was the most effective in inducing germination, and far-red light was ineffective. Exposure to red light for 1 min increased germination; this effect was saturated at an exposure of2 min. The red-light effect was reversed by subsequent exposure to far-red light. The results indicate that rose seeds are positively photoblastic, and that the photoreceptor involved is most likely phytochrome.